Pgmdeshadow User Manual(0) Pgmdeshadow User Manual(0)NAME
pgmdeshadow - Deshadow a PGM image
SYNOPSIS
pgmdeshadow
[pnmfile]
DESCRIPTION
This program is part of Netpbm(1)
pgmdeshadow removes gray shadows from an image. This is useful for an image containing
text, such as a scanned book pages, where a shadow typically appears near the book crease
or near one side of the image. pgmdeshadow recognizes a gray shadow as an area of
smoothly changing color, starting from the outer edges of the image. The program uses a
simple image reconstruction algorithm to determine the local shadow gray level, then
divides each pixel's gray level by the local shadow gray level.
The algorithm is the 'fast hybrid grayscale reruction' algorithm from Luc Vincent, "Mor-
phological Grayscale Reruction in Image Analysis: Applications and Efficient Algorithms.
OPTIONS
None.
REFERENCES
o Luc Vincent, 'Morphological Grayscale Reruction in Image Analysis: Applications and
Efficient Algorithms,' IEEE Transactions on Image Processing, vol. 2, no. 2, April
1993, pp. 176-201.
SEE ALSOppmshadow(1) , pgm(1)HISTORY
pgmdeshadow was added to Netpbm in Version 10.35 (August 2006).
netpbm documentation 06 July 2006 Pgmdeshadow User Manual(0)